Browsing by Subject "Pieris brassicae"

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  • Rajanen, Hanne (Helsingfors universitet, 2011)
    The forest industry achieves each year large quantities of waste material, such as wood, bark and branches. The waste material is mainly used for energy production, but new applications are being investigated. The bark has been identified as a potential source of numerous bioactive compounds, which would have use, for example, in the pharmaceutical and chemical industries as well as in the pest management of agriculture, forestry and horticulture. The thesis is part of the European Union-funded ForestSpeCs project, which aims to find alternative ways to use the materials of forest industry. The bark extracts of ten economically remarkable northern trees were tested for possibilities as antifeedants for the larvae of the cabbage white (Pieris brassicae L.), the Egyptian cotton leafworm (Spodoptera littoralis Boisduwal), and some of them also for the mustard leaf beetle (Phaedon cochleariae Fabricius) and the alder leaf beetle (Agelastica alni L.). The extracts were prepared in cooperation with the project groups or independently using different methods. Testing was carried out in laboratory conditions by using the dual-choice leaf-disc bioassays for the crude extracts and the individual compounds separated from them. The feeding deterrent indices (FDI) were calculated from the measurements. On the basis of the results, nearly all the tested extracts, at least to some extent, appeared to have an effect on the insect’s eating behavior. Slightly more than half of the 46 extracts tested with the cabbage white caused more than 50% feeding deterrence, in other words the cabbage butterfly preferred the control leaves more often than the treated ones. For Egyptian cotton leafworm larvae over 50% feeding deterrence was caused only by the seven of the tested 56 extracts. In addition, three of the extracts stimulated the consuming of the treated leaves significantly. The alder leaf beetle larvae and adults were deterred by the leaves treated with abietic acid, in particular. The extracts tested on the mustard leaf beetle were also working promisingly. It is possible to extract biologically active compounds from the bark of the tested tree species, but it is necessary, in the context of pest management, to have more research on the correct concentrations of the extracts and effective extracting methods. The quality and quantity of compounds in the bark depend on many factors, such as the impact of the environment and genetics. Tolerance in insects varies a lot by species and there are also differences between individuals. The pesticides manufactured of extracts could be possible to include in the integrated pest management alongside the other methods in the future.